The analysis of data from more than 184,000 women is the biggest of three major studies to conclude that drinking raises the risk of breast cancer for older women, Jasmine Lew, a researcher at the National Cancer Institute and the study's lead investigator said on Sunday.

The research found that women who had one to two small drinks a day were 32 percent more likely to develop a hormone-sensitive tumor. Three or more drinks a day raised the risk by 51 per cent.

Researchers found that among more than 24,000 middle-aged and older Japanese women, those with the highest levels of the compound, called genistein, were only one-third as likely as other women to develop breast cancer over 10 years.

Genistein is one of the major isoflavones, plant compounds found in soybeans, chick peas and other legumes that are structurally similar to the hormone estrogen, and are believed to bind to estrogen receptors on body cells.